Silicone composition used in the production of antifriction varnishes, method for the application of said varnishes to a support and support thus treated

ABSTRACT

A silicone composition which can be used in the production of varnishes that can be applied to supports to reduce the friction coefficient. The silicone composition includes at least one polyorganosilane A (POS) which can be cationically and radically cross-linked by functional cross-linking groups (GER) and a primer C chosen from onium borates. The composition also includes molecules (POS D) which are substituted by secondary functional groups (GFS) caned by silicon atoms and selected from those that include at least one alkoxy and/or epoxy and/or carboxy motif and optionally a charge (e.g. silica). The composition can be used with antifriction varnishes for RTV silicone coatings for material used in airbags, thermal transfer ribbons or packing films

This application is a continuation of Ser. No. 09/958,179, now U.S. Pat.No. 6,902,816, which is a U.S. National Stage of Internationalapplication PCT/FR00/00861, filed Apr. 5, 2000.

TECHNICAL FIELD

The general field of the invention is that of polymer coatings orvarnishes capable of conferring anti-friction properties on substrates.More precisely, the invention relates to silicone compositions useful inparticular for the production of varnishes which can be applied tosupports whose coefficient of friction it is sought to reduce. Thesupports in question are varied and may consist in particular:

-   -   of woven or nonwoven fibrous substrates coated with at least one        layer for protection or for mechanical reinforcement, based on a        coating polymer of the silicone elastomer type for example;    -   of polymer substrates, in particular plastic films such as for        example:        -   thermal transfer ribbons which can be used in particular as            support for ink in thermal transfer printers,        -   or protective wrapping films,

The present invention also relates to the methods for applying theanti-friction varnish to which it relates, to various supports.

Finally, the subject of the invention is the supports coated with suchanti-friction varnishes and, in particular:

-   -   textile fabrics coated with an elastomer layer onto which the        anti-friction varnish is applied, such fabrics being capable of        being used for the manufacture of bags for the personal        protection of the occupants of vehicles, also called air bag,    -   thermal transfer ribbons consisting for example of plastic films        (e.g. made of polyester) carrying ink and which can be used in        thermal transfer printers,    -   protective wrapping films.

PRIOR ART

The general problem forming the basis of the invention is thedevelopment of an anti-friction silicone varnish. This problem ofreducing coefficients of friction is posed with particular intensity forsubstrates coated with crosslinked elastomeric silicone coatings.Indeed, it is well known to persons skilled in the art that coatinglayers made of elastomeric silicone have a sticky feel which is damagingfor numerous applications.

As regards more precisely the air bag application, it is known thatthese inflatable bags for the personal protection of the occupants ofvehicles are made from a synthetic fiber fabric, for example made ofpolyamide (nylon®), coated on at least one of its sides with a layer ofan elastomer which may be a silicone elastomer which is coldcrosslinkable or vulcanizable by polyaddition (CVEII), polycondensation(CVEI), a silicone elastomer which is hot crosslinkable or vulcanizableby polycondensation with peroxide or by polyaddition (HVE) or a viscoussilicone elastomer which is crosslinkable or vulcanizable bypolyaddition of the LSR type.

This protective coating for example made of silicone is at leastinternal and makes it possible to guard against the effects of theexplosion from the inflating of the bag. The fact that the elastomericsilicone coating has a sticky feel constitutes an impediment on theopening of the bag. Improving the efficiency of the air bags thereforeinvolves making them from a coated material with a low coefficient offriction.

For further details on air bags for personal protection, reference maybe made in particular to French patent No. 2 668 106 and more especiallyto French patent No. 2 719 598 for air bags coated with an RTV siliconeelastomer which is crosslinkable by polyaddition.

This search for a low coefficient of friction for coatings on substratescoated or otherwise with silicone elastomer is also a concern in otherapplications such as, for example, coatings for thermal transfer ribbons(e.g. made of polyester) or protective wrapping films (e.g. made ofpolyethylene or made of polypropylene.

The thermal transfer ribbons can be used in thermal transfer printers.These thermal transfer ribbons are very thin (a few microns) and arecoated, on one of their surfaces, with a layer of ink (waxes or resins)and on the other surfaces, with a protective coating. A very thinprotective coating having a thickness of between 0.1 and 1 micrometer isgenerally used to protect the surface of the film and to improve theimpact of the printing head without deforming the transfer of the inkonto the applied support.

In printers whose printing speed is between 150 and 300 mm/s, it is veryimportant for the printing head (flat or wedge-shaped), when it strikesthe protective coating of the ribbon, to slide on the surface of thecoating, at a high temperature of between 100 and 200° C.

As regards protective wrapping films, it is sometimes envisaged to applyon them a silicone-based top varnish in order to confer anti-adhesionproperties on them.

However, it is advisable for this top varnish to possess a slipperinesswhich is at least equivalent to that of the starting plastic film(imprinted or otherwise).

BRIEF DISCLOSURE OF THE INVENTION

Faced with this problem, one of the essential objectives of the presentinvention is to propose to reduce the coefficient of friction of thesubstrate which may be coated with a coating layer, for example made ofsilicone, using an anti-friction varnish.

Another essential objective of the present invention is to provide ananti-friction varnish which can be easily applied to various types ofsubstrates.

Another essential objective of the invention is to provide acrosslinkable anti-friction varnish which is easy and economical to use.

Another essential objective of the invention is to provide a siliconecomposition which can be used in particular for the production of ananti-friction varnish of the type mentioned above.

Another essential objective of the present invention is to provide asilicone composition which is useful in particular for the production ofan anti-friction varnish, it being necessary for this composition tohave a reasonable cost price and to be simple to prepare.

Another essential objective of the invention is to provide ananti-friction varnish consisting of a crosslinkable siliconecomposition, capable of significantly reducing the coefficient offriction of various types of coated or uncoated substrates.

Another objective of the invention is to provide a simple and economicalmethod of applying an anti-friction varnish based on a siliconecomposition to various supports consisting, for example, of woven ornonwoven fibrous substrates and optionally coated, for example, with alayer of crosslinked silicone elastomer.

Another essential objective of the invention is to provide a fabriccoated with crosslinked silicone elastomer intended for the manufactureof air bags, it being necessary for such a fabric to have a lowcoefficient of friction.

Another essential objective of the invention is to provide a fabriccoated with a crosslinked elastomeric silicone for the manufacture ofair bags, coated with an anti-friction varnish based on a siliconecomposition.

Another essential objective of the invention is to provide a fibroussupport, for example a fabric, coated with a crosslinked elastomericcoating and endowed with a static coefficient of friction (Ks)corresponding to the force necessary to initiate the movement of arectangular mass covered with the fabric in question on a flat glasssupport at a value of Ks≦1, for a coating deposit all layers stickingtogether D<20 g/m².

These objectives, among others, are achieved by the present inventionwhich relates, in the first place, to a silicone composition useful inparticular for the production of varnish having in particularanti-friction properties, this composition being of the type comprisingat least one polyorganosiloxane (POS) which can be crosslinked by meansof crosslinking functional groups (CFG) by the cationic and/orfree-radical route and an effective quantity of a cationic initiatorsystem comprising, as thermal initiator and/or photoinitiator, a productchosen from the onium salts of an element of groups 15 to 17 of thePeriodic Table [Chem & Eng. News, vol. 63, No. 5, of 4 Feb. 1985] or thesalts of an organometallic complex of an element of groups 4 to 10 ofthe Periodic Table [same reference],

-   -   whose cationic entity is selected from:        -   1) the onium salts of formula (I):            [(R¹)_(n)-A-(R²)_(m)]⁺  (I)        -    in which formula:            -   A represents an element of groups 15 to 17 such as for                example: I, S, Se, P or N,            -   R¹ represents a carbocyclic or heterocyclic C₆-C₂₀ aryl                radical, it being possible for said heterocyclic radical                to contain, as heteroelements, nitrogen or sulfur;            -   R² represents R¹ or a linear or branched C₁-C₃₀ alkyl or                alkenyl radical, said radicals R¹ and R² being                optionally substituted with a C₁-C₂₅ alkoxy, C₁-C₂₅                alkyl, nitro, chloro, bromo, cyano, carboxyl, ester or                mercapto group;            -   n is an integer ranging from 1 to v+1, v being the                valency of the element A,            -   m is an integer ranging from 0 to v−1 with n+m=v+1,        -   2) the oxoisothiochromanium salts described in patent            application WO 90/11303, in particular the sulfonium salt of            2-ethyl-4-oxoisothiochromanium or of            2-dodecyl-4-oxoisothiochromanium,        -   3) the sulfonium salts in which the cationic entity            comprises:            -   3.1. at least one polysulfonium species of formula                III.1.

-   -   -   -    in which:

        -   the symbols Ar¹, which may be mutually identical or            different, each represent a monovalent phenyl or naphthyl            radical optionally substituted with one or more radicals            chosen from: a linear or branched C₁-C₁₂, preferably C₁-C₆,            alkyl radical, a linear or branched C₁-C₁₂, preferably            C₁-C₆, alkoxy radical, a halogen atom, an —OH group, a —COOH            group, an ester group —COO-alkyl where the alkyl portion is            a linear or branched C₁-C₁₂, preferably C₁-C₆, residue, and            a group of formula —Y⁴—Ar² where the symbols Y⁴ and Ar² have            the meanings given just below,

        -   the symbols Ar², which may be mutually identical or            different or with Ar¹, each represents a monovalent phenyl            or naphthyl radical optionally substituted with one or more            radicals chosen from: a linear or branched C₁-C₁₂,            preferably C₁-C₆, alkyl radical, a linear or branched            C₁-C₁₂, preferably C₁-C₆, alkoxy radical, a halogen atom, an            —OH group, a —COOH group, an ester group —COO-alkyl where            the alkyl portion is a linear or branched C₁-C₁₂, preferably            C₁-C₆, residue,

        -   the symbols Ar³, which may be mutually identical or            different, each represent a divalent phenylene or            naphthylene radical optionally substituted with one or more            radicals chosen from: a linear or branched C₁-C₁₂,            preferably C₁-C₆, alkyl radical, a linear or branched            C₁-C₁₂, preferably C₁-C₆, alkoxy radical, a halogen atom, an            —OH group, a —COOH group, an ester group —COO-alkyl where            the alkyl portion is a linear or branched C₁-C₁₂, preferably            C₁-C₆, residue,

        -   t is an integer equal to 0 or 1,

        -    with the additional conditions according to which:            -   when t=0, the symbol Y is then a monovalent radical Y¹                representing the group of formula:

-   -   -   -    where the symbols Ar¹ and Ar² have the meanings given                above,            -   when t=1:            -   on the one hand, the symbol Y is then a divalent radical                having the following meanings Y² to Y⁴:                -   Y²: a group of formula:

-   -   -   -   -    where the symbol Ar² has the meanings given above,                -   Y³: a single valency bond,                -   Y⁴: a divalent residue chosen from:

-   -   -   -   -    a linear or branched C₁-C₁₂, preferably C₁-C₆,                    alkylene residue, and a residue of formula                    —Si(CH₃)₂O—,

            -   on the other hand, in the case solely where the symbol Y                represents Y³ or Y⁴, the radicals Ar¹ and Ar² (terminal)                possess, in addition to the meanings given above, the                possibility of being linked to each other by the residue                Y′ consisting in Y′¹ a single valency bond or in Y′² a                divalent residue chosen from the residues cited in                relation to the definition of Y⁴, which is seated                between the carbon atoms, facing one another, situated                on each aromatic ring at the ortho position with respect                to the carbon atom directly linked to the cation S⁺;                -   3.2. and/or at least one mono-sulfonium species                    possessing a single cationic center S+per mol of                    cation and consisting in most cases in species of                    formula:

-   -   -   -    in which Ar¹ and Ar² have the meanings given above in                relation to formula (III.1), including the possibility                of directly linking to one another only one of the                radicals Ar¹ to Ar² in the manner indicated above in                relation to the definition of the additional condition                which applies when t=1 in formula (III.I), involving the                residue Y′;

        -   4) the organometallic salts of formula (IV):            (L¹L² L³M)⁺q  (IV)

        -    in which formula:            -   M represents a metal of group 4 to 10, in particular                iron, manganese, chromium, cobalt and the like            -   L¹ represents 1 ligand linked to the metal M by π                electrons, a ligand chosen from the ligands η³-alkyl,                η⁵-cyclopendadienyl and η⁷-cycloheptratrienyl and the                η⁶-aromatic compounds chosen from the optionally                substituted η⁶-benzene ligands and the compounds having                from 2 to 4 fused rings, each ring being capable of                contributing to the valency layer of the metal M by 3 to                8 π electrons;            -   L² represents a ligand linked to the metal M by π                electrons, a ligand chosen from the ligands                η⁷-cycloheptatrienyl and the η⁶-aromatic compounds                chosen from the optionally substi-tuted η⁶-benzene                ligands and the compounds having from 2 to 4 fused                rings, each ring being capable of contributing to the                valency layer of the metal M by 6 or 7 π electrons;            -   L³ represents from 0 to 3 identical or different ligands                linked to the metal M by σ electrons, ligand(s) chosen                from CO and NO₂ ⁺; the total electron charge q of the                complex to which L¹, L² and L³ contribute and the ionic                charge of the metal M being positive and equal to 1 or                2;

    -   the anionic entity having the formula:        [X¹X² _(a)R_(b)]—

    -    in which formula:        -   a and b are integers ranging, for a, from 0 to 6 and, for b,            from 0 to 6 with a+b≧2;        -   the symbols X¹ represent elements chosen from groups IIIA,            IVA, VA of the Periodic Table, preferably from the group            comprising: B, P and Sb;        -   the symbols X² represent:            -   a halogen atom (chlorine, fluorine) with a=0 to 3,            -   an OH functional group with a=0 to 2,        -   the symbols R are identical or different and represent:            -   a phenyl radical substituted with at least one                electron-attracting group such as for example OCF₃, CF₃,                NO₂, CN, and/or with at least 2 halogen atoms (fluorine                most particu-larly), and this being when the cationic                entity is an onium of an element of groups 15 to 17,            -   a phenyl radical substituted with at least one element                or one electron-attracting group, in particular a                halogen atom (fluorine most particularly), CF₃, OCF₃,                NO₂, CN, and this being when the cationic entity is an                organo-metallic complex of an element of groups 4 to 10            -   an aryl radical contain-ing at least two aromatic nuclei                such as for example biphenyl, naphthyl, optionally                substituted with at least one element or one                electron-attracting group, in particular a halogen atom                (fluorine most particularly), OCF₃, CF₃, NO₂, CN,                regardless of the cationic entity;        -   this composition being characterized in that it comprises,            in addition, molecules substituted with secondary functional            groups (SFG) carried by at least one silicon atom per            molecule and preferably selected from those comprising at            least one alkoxy and/or enoxy and/or carboxyl unit.

The silicone varnish composition according to the invention isadvantageous in that it can be easily and industrially crosslinked bythe cationic and/or free-radical route, by exposing to a beam ofelectrons and/or to actinic radiation of the UV type and/or by thermalactivation. Once applied and crosslinked on a support, this varnishconfers significant antifriction characteristics thereon.

These advantageous results stem from the judicious selection of asilicone varnish composition comprising compounds in which the siliconatoms (POS-silanes) carry crosslinking functional groups CFG as well asfunctional groups SFG, advantageously of alkoxy and/or enoxy and/orcarboxyl type. The SFGs have a significant role in providing theantifriction properties to the coating composition. The fact that thissilicone varnish composition can be easily applied and crosslinked on asupport, for example a fabric or a plastic film, also stems from the useof a specific photoinitiator family of the type described in Frenchpatent application No. 96 16237 whose entire content is included byreference in the present application. Such photoinitiators allow rapidand complete photocrosslinking of the varnish.

DETAILED DISCLOSURE OF THE INVENTION

According to a first embodiment of the invention, the silicone varnishcomposition comprises:

-   -   A—at least one POS carrying CFGs, the latter being preferably        chosen from the groups comprising at least one ethylenically        unsaturated functional group—advantageously acrylate and/or        alkenyl ether—and/or epoxide and/or oxethane;    -   B—at least one silane and/or one POS carrying SFGs, the latter        preferably representing at least 0.5% and more preferably still        at least 1% by weight of B;    -   C—at least one photoinitiator system as defined above.

In this first embodiment, the CFGs, on the one hand, and the SFGs, onthe other hand, are carried by different molecules or macromoleculesbased on silicon.

The alternative which corresponds to the second embodiment of theinvention is that these silicon-based molecules are substituted bothwith CFG groups and with SFG groups. In this case, the silicone varnishcomposition according to the invention comprises:

-   -   C—at least one photoinitiator system as defined above,    -   D—at least one POS carrying CFGs and SFGs,        the CFGs being preferably chosen from groups comprising at least        one ethylenically unsaturated functional group—    -   advantageously acrylate and/or alkenyl ether—and/or epoxide        and/or oxethane;

Naturally, it is not impossible for the composition according to theinvention to comprise the POSs and/or the silanes A, B, D, together.

These hardening (for example under UV and/or under a beam of electrons)varnish compositions providing surface antifriction properties maycomprise in addition:

-   -   F—optionally at least one organic reactive diluent chosen from        organic resins of the epoxide and/or vinyl ether and/or oxethane        type;    -   G—optionally at least one organic or inorganic pigment;    -   H—optionally a filler, preferably a silicic filler;    -   I—optionally at least one photosensitizer, preferably selected        from (poly)aromatics (optionally metallic) and/or heterocyclics.

Entering into detail on the nature of the various constituents of thesilicone varnish composition according to the invention, it will bespecified, as regards the POSs A, that they are preferablyepoxysilicones and/or vinyl ether silicones which are:

-   -   either linear or substantially linear and consist of units of        formula II.1, ending with units of formulae (II.2)    -   or cyclic and consisting of units of formula (11.1):

-   -    in which formulae:    -   the symbols R¹ are similar or different and represent:        -   either a linear or branched C₁-C₆ alkyl radical optionally            advantageously substituted with one or more halogens, the            preferred optionally substituted alkyl radicals being:            methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl,        -   or an optionally substituted C₁-C₈ cycloalkyl radical,        -   or an aryl or aralkyl radical optionally substituted:        -   in particular with halogens and/or alkoxyls,        -   the phenyl, xylyl, tolyl and dichlorophenyl radicals being            most particularly selected,        -   and, more preferably still, at least 60 mol % of the R³            radicals being methyls,    -   the symbols Z are similar or different and represent:        -   either the radical R¹,        -   or a CFG group corresponding to an epoxide or vinyl ether            residue linked to the silicon by means of a divalent radical            advantageously containing from 2 to 20 carbon atoms            optionally comprising a heteroatom,    -   at least one of the symbols Z corresponding to a CFG group.

As examples of organofunctional CFG groups of the epoxy type, there maybe mentioned those of the following formula:

As regards the organofunctional CFG groups of the vinyl ether type,there may be mentioned, e.g., those contained in the following formulae:

-   -   with R⁴⁰═    -   optionally substituted linear or branched C₁-C₁₂ alkylene,    -   or arylene, preferably phenylene, optionally substituted        preferably with one to three C₁-C₆ alkyl groups;    -   with R⁵⁰=linear or branched C₁-C₆ alkyl.

The preferred epoxy or vinyloxyfunctional polyorganosiloxanes aredescribed in particular in patents DE-A-4 009 889; EP-A-0 396 130;EP-A-0 355 381; EP-A-0 105 341; FR-A-2 110 115; FR-A-2 526 800.

The functional epoxy polyorganosiloxanes may be prepared byhydrosilylation reaction between oils with Si—H units andepoxyfunctional compounds, such as 4-vinylcyclohexene oxide, allylglycidyl ether and the like.

The vinyloxyfunctional polyorganosiloxanes may be prepared byhydrosilylation reaction between oils with Si—H units andvinyloxyfunctional compounds, such as allyl vinyl ether,allyl-vinyloxyethoxybenzene and the like.

More preferably still, the POSs A are epoxysilicones of the followingformulae (A.I) (A.II):

with X═CH₃; Phenyl; Cycloalkyl; C₁-C₈ alkyl; alkenyl; —OH; H;CH₂—CH₂—CH₂—OH; CH₂—CH₂—CF₃; —(CH₂)_(n)—CF₃, n=1 to 20;

-   -   a₁, a₂ and b₁, b₂ being defined as below in these formulae (A.I)        and (A.II)        1≦a₁, a₂ 1≦b₁, b₂        preferably 1≦a₁, a₂≦5 000 1≦b₁, b₂≦500        and more preferably still 1≦a₁, a₂≦1 000 1≦b₁, b₂≦100;    -   a₂, b₂ being=0 in formula (A.II) to give the epoxydized        disiloxane (A.III).

According to another advantageous characteristic of the invention, thePOS(s) (A) has (have) a viscosity η (expressed in mPa·s at 25° C.) ofbetween:

-   -   200 and 3 000,        -   preferably 300 and 2 000,        -   and more preferably still between 400 and 900.

These viscosity values relate both to the linear POSs and the cyclicPOSs which are capable of being used in accordance with the useaccording to the invention.

The dynamic viscosity at 25° C. of all the silicone polymers consideredin the present disclosure may be measured using a BROOKFIELD viscometer,according to the AFNOR standard NFT 76 102 of February 1972.

The viscosity in question in the present disclosure is the dynamicviscosity at 25° C., called “Newtonian” viscosity, that is to say thedynamic viscosity which is measured, in a manner known per se, at asufficiently low shearing speed gradient for the measured viscosity tobe independent of the speed gradient.

In accordance with the invention, it is perfectly possible to envisageusing a mixture of various POSs A with units of formulae (II.1) and(II.2), as defined above (linear and/or cyclic).

As regards the compound(s) B, it is advantageous in accordance with theinvention that it/they is/are chosen from that (or those) of thefollowing formula B:R² _(x)[SFG]_(y)SiO_(4−(x+y)/2)  (B)in which:

-   -   x=0, 1, 2 or 3    -   y=1, 2, 3 or 4    -   the radicals R² are mutually identical or different and        correspond to a linear or branched alkyl, a cycloalkyl, a        hydroxyl, a hydrogen, a vinyl, a —CF₃, a —(CH₂)_(m)—CF₃ with m=1        to 50,    -   the SFGs are mutually identical or different and correspond to        -   an alkoxy, preferably: —OR³ with R³ representing a linear or            branched C₁-C₃₀ alkyl or a cycloalkyl;            -   —(OR⁴)_(n)—OR⁵; —(R⁶)_(q)—Si(OR⁷)_(r)(R⁸)_(t)                -   with R⁴, R⁷, R⁸ mutually identical or different and                    having the same definition as that given above for                    R³ and with R⁶ mutually identical or different and                    preferably corresponding to an alkylene                    (advantageously a methylene);                -   p, q=1 to 50, preferably 1 to 10;                -   r=1, 2 or 3 and t=0, 1 or 2;                -    an enoxy, preferably:                -   —O—CH═CH—R⁸;                -   —(R⁹)_(u)—Si(OCH═CHR10)_(v)(R¹¹)_(w);                -   with R⁸, R¹⁰, R¹¹ mutually identical or different                    and having the same definition as that given above                    for R³, and with R⁹ having the same definition as                    that given above for R⁶;                -   u=1 to 50, preferably 1 to 10,                -   v=1, 2 or 3 and w=0, 1 or 2;                -    a carboxyl, preferably:                -   —OCOR²;                -   —(R¹³)_(z)—Si(OCOR¹⁴)_(z1)(R¹⁵)_(z2);                -   with R¹², R¹⁴ as defined above for R⁸, R¹⁰, R¹¹;                -   R¹³ as defined above for R⁹; and                -   z=1 to 50, preferably 1 to 10, z₁=1, 2 or 3 and                    z₂=0, 1 or 2;

By way of example of POS B, there may be mentioned:

with Et=ethyl.

By way of example of silane B, there may be mentioned: MeSi(OEt)₃;Si(OEt)₄; PrSi(OEt)₃; OctSi(OMe)₃; PrSi(OMe)₃; and the like

with Me=methyl; Et=ethyl; Pr=propyl, Oct=octyl.

In accordance with the second embodiment, mixed POSs D comprising bothCFGs and SFGs are used. Without that being limiting, it is found thatthis second embodiment is more especially preferred. Thus, the POSs Dused advantageously comprise SFGs as defined above and CFGs of theepoxide type.

More preferably still, said POS D corresponds to the POSs of thefollowing formulae (D′, D″, D′″):

with0≦d₁ 1≦d₂ 1≦d₃preferably 0≦d₁≦5 000 1≦d₂≦500 1≦d₃≦500and more preferably still 0≦d₁≦1 000 1≦d₂≦100 1≦d₃≦100

with Me=methyl; Et=ethyl0≦epreferably 0≦e≦5 000 and more preferably still 0≦e≦1 000

In the case where the compound D is a silane comprising both CFGs of the(Meth)acrylate and/or vinyl ether and/or epoxide and/oroxethane—preferably epoxide—type—as well as SFGs—preferably of thealkoxy type—, it may include for example the following compounds:

According to a preferred characteristic of the invention, the initiatorsC are e.g.: the onium borates described in European patent applicationNo. 0 562 922 whose entire content is included by reference in thepresent application. More precisely still, there may be used in practicethe initiator of the following formula:

In practice, the initiators for the use according to the invention areprepared in a very simple manner by dissolving the onium borate ororganometallic complex, preferably of onium, provided in solid (powder)form in a solvent.

According to one alternative relating to onium borate, the latter may beprepared directly in the solvent, from a salt (e.g. chloride) of thecation (iodonium) and a salt (for example of potassium) of the borateanion.

Preferably, it is envisaged in accordance with the use according to theinvention that the initiator is used in solution in an organic solvent,preferably chosen from solvents which are proton donors and morepreferably still from the following group: isopropyl alcohol, isobenzylalcohol, diacetone alcohol, butyl lactate, esters, and mixtures thereof.As is claimed in French patent No. 2 724 660, organic solvents which areproton donors and which have an aromatic character (benzyl alcohol)behave as crosslinking accelerators. It is therefore advantageous to usethem to dissolve the photoinitiator.

It should be specified that the expression effective catalytic quantityof photoinitiator is understood to mean, for the purposes of theinvention, the quantity sufficient to initiate the crosslinking.

Since in practice—as indicated above—the photoinitiator isadvantageously dissolved in a polar solvent, in a quantity such that itstiter in the solution obtained is between 1 and 50% by weight,preferably between 10 and 30% by weight, and more preferably stillbetween 15 and 25% by weight.

According to an advantageous feature of the use according to theinvention, the incorporation of the photoinitiator in solution into thecomposition comprising the POS at a given molar content of CFG iscarried out at the rate of 0.1 to 10% by weight of solution relative tothe final mixture and preferably 0.5 to 5% by weight and more preferablyof the order of 1% by weight.

According to one variant of the use in accordance with the invention,crosslinking inhibitors may be used which are preferably chosen fromalkaline products, and more preferably still from alkaline products ofthe amine-containing type, for example of the type consisting of asilicone onto which at least one amine group, preferably a tertiaryamine group, is grafted.

As regards the optional additives, there may be mentioned in relation tothe optional reactive diluent E that the compounds of formula E′(epoxide) and E″ (vinyl ether) are examples among others:

The optional inorganic or organic pigments F are added to give color tothe silicone varnish according to the invention. In particular, thiscolor makes it possible to recognize a nonvarnished fabric from avarnished fabric merely at a glance.

By way of examples of pigments, there may be mentioned carbon black;titanium dioxide; phthalocyanin; benzimidazolone; naphthols (BONApigment lakes); diazopyrazolones; diarylide or monoarylide yellowpigments and the like.

The fillers G and in particular the silicic fillers may be for examplepyrogenic silicas treated with hexamethyldisilasanes or withoctamethylcyclotetrasiloxanes (specific surface area 300 m²/g), fumedsilica.

These fillers may be inorganic or otherwise, e.g.: ground synthetic ornatural fiber (polymers), calcium carbonate, talc, clay, titaniumdioxide and the like.

As regards the optional photosensitizers H, they may be selected from(poly)aromatic products—optionally metallic—and heterocyclic products,and preferably from the list of the following products: phenothiazine,tetracene, perylene, anthracene, 9,10-diphenylanthracene, thioxanthone,benzophenone, acetophenone, xanthone, fluorenone, anthraquinone,9,10-dimethylanthracene, 2-ethyl-9,10-dimethyloxyanthracene,2,6-dimethylnaphthalene, 2,5-diphenyl-1-3-4-oxadiazole, xanthopinacol,1,2-benzanthracene, 9-nitroanthracene, and mixtures thereof.

More especially, they may be a product H based on thioxanthone:

Taking into account its ease of production its low cost and itsantifriction properties, the silicone varnish according to the inventionmay have uses in numerous fields of application and in particular in thefield of the coating of woven or nonwoven fibrous supports.

It follows therefrom that the invention relates, according to another ofits aspects, to the application of the composition as described above asantifriction varnish to a support, this support preferably comprising asubstrate—advantageously fibrous (and more especiallytextile)—optionally coated with at least one silicone elastomer layerwhich is at least partially crosslinked.

Advantageously, this method of application essentially consists:

-   -   in coating a support with the varnish composition as defined        above,    -   and in exposing the surface thus coated to actinic radiation        and/or to a beam of electrons and/or to heat, so as to cause the        crosslinking of the varnish layer.

The means of applying the layer of noncrosslinked varnish to the supportare of the type known and appropriate for this purpose (bar or roll forcoating). The same applies as regards the means of exposing, forexample, to UV radiation and/or to the electron beams.

Other details will be given in this regard in the examples which follow.

The present invention also relates to the varnish support endowed withantifriction properties, as obtained by the above-defined application.

According to a preferred embodiment of this varnish support, the lattercomprises a substrate—preferably textile—coated on at least one of itssurfaces with at least one layer of silicone elastomer which can becrosslinked or which is at least partially crosslinked, preferablychosen from:

-   -   the polyaddition or polycondensation RTV silicones,    -   and/or the peroxide HVE silicones,    -   and/or the polyaddition LSR silicones,    -   the antifriction varnish obtained from the composition as        defined above being applied to the (top) layer(s) of silicone        elastomer. The expressions RTV, LSR and HVE are well known to        persons skilled in the art: RTV is the abbreviation for “room        temperature vulcanizing”; LSR is the abbreviation for “liquid        silicone rubber”; HVE is the abbreviation for hot vulcanizable        elastomer.

In practice, the invention relates more precisely to the supports (forexample textiles such as those used for the manufacture of air bags)coated on one and/or the other of their surfaces with a layer ofcrosslinked silicone elastomer RTV, HVE or LSR, itself coated with acoating of antifriction silicone varnish as defined above.

The problem of providing antifriction properties is particularly acuteas regards these crosslinked silicone elastomer coatings since asalready indicated above the latter have the characteristic of having asticky feel.

The polyorganosiloxanes, principal constituents of the sticky layers ofcrosslinked elastomers onto which the varnish according to the inventionmay be applied, may be linear, branched or crosslinked, and may comprisehydrocarbon radicals and/or reactive groups such as for example hydroxylgroups, hydrolysable groups, alkenyl groups and hydrogen atoms. Itshould be noted that the polyorganosiloxane compositions are fullydescribed in the literature and in particular in the book by WalterNOLL: “Chemistry and Technology of Silicones”, Academic Press, 1968, 2ndedition, pages 386 to 409.

More precisely, these varnishable polyorganosiloxanes consist of siloxylunits of general formula:

$\begin{matrix}{R\;{^\circ}_{n1}{SiO}_{\frac{x - n_{1}}{2}}} & ( I^{\prime} )\end{matrix}$and/or siloxyl units of formula:

$\begin{matrix}{Z\;{^\circ}_{x_{1}}R\;{^\circ}_{y_{1}}{SiO}_{\frac{4 - x_{1} - y_{1}}{2}}} & ( {II}^{\prime} )\end{matrix}$in which formulae the various symbols have the following meaning:

-   -   the symbols R^(o), which are identical or different, each        represent a group of a nonhydrolysable hydrocarbon nature, it        being possible for this radical to be:        -   an alkyl radical, a haloalkyl radical having from 1 to 5            carbon atoms and comprising from 1 to 6 chlorine atoms            and/or fluorine atoms,        -   cycloalkyl and halocycloalkyl radicals having from 3 to 8            carbon atoms and containing from 1 to 4 chlorine and/or            fluorine atoms,        -   aryl, alkylaryl and haloaryl radicals having from 6 to 8            carbon atoms and containing from 1 to 4 chlorine and/or            fluorine atoms,        -   cyanoalkyl radicals having from 3 to 4 carbon atoms;    -   the symbols Z^(o), which are identical or different, each        represent a hydrogen atom, a C₂-C₆ alkenyl group, a hydroxyl        group, a hydrolysable atom, a hydrolysable group;    -   n₁=an integer equal to 0, 1, 2 or 3;    -   x₁=an integer equal to 0, 1, 2 or 3;    -   Y₁=an integer equal to 0, 1 or 2;    -   the sum x+y is between 1 and 3.

By way of illustration, there may be mentioned among the organicradicals R^(o) directly linked to the silicon atoms: the groups methyl;ethyl; propyl; isopropyl; butyl; isobutyl; n-pentyl; t-butyl;chloromethyl; dichloromethyl; α-chloroethyl; α,β-dichloroethyl;fluoromethyl; difluoromethyl; α,β-difluoroethyl; 3,3,3-trifluoropropyl;trifluorocyclopropyl; 4,4,4-trifluorobutyl;3,3,4,4,5,5-hexafluoropentyl; β-cyanoethyl; γ-cyanopropyl; phenyl:p-chlorophenyl; m-chlorophenyl; 3,5-dichlorophenyl; trichlorophenyl;tetrachlorophenyl; o-, p- or m-tolyl; α,α,α-trifluorotolyl; xylyl like2,3-dimethylphenyl, 3,4-dimethylphenyl.

Preferably, the organic radicals R^(o) linked to the silicon atoms aremethyl or phenyl radicals, it being possible for these radicals to beoptionally halogenated or even cyanoalkyl radicals.

The symbols Z^(o) may be hydrogen atoms, hydrolysable atoms such ashalogen atoms, in particular chlorine atoms, vinyl or hydroxyl groups orhydrolysable groups such as for example: amino, amido, aminoxy, oxime,alkoxy, alkenyloxy, acyloxy.

The nature of the polyorganosiloxane and therefore the ratios betweenthe siloxyl units (I′) and (II″) and the distribution thereof is, as isknown, chosen according to the crosslinking treatment which will becarried out on the curable (or vulcanizable) composition with a view toits conversion to an elastomer.

It is possible to use a large variety of monocomponent or bicomponentcompositions which can be crosslinked by polyaddition orpolycondensation reactions, in the presence of a metal catalyst andoptionally of an amine and of a crosslinking agent.

The bicomponent or monocomponent polyorganosiloxane compositions whichcrosslink at room temperature (RTV) or with heat (HVE) by polyadditionreactions, essentially by reaction of hydrogenosilylated groups withalkenylsilylated groups, in the presence generally of a metal catalyst,preferably platinum, are described for example in patents U.S. Pat. Nos.3,220,972, 3,284,406, 3,436,366, 3,697,473 and 4,340,709. Thepolyorganosiloxanes entering into these compositions consist in generalof pairs based, on the one hand, on a linear, branched or crosslinkedpolysiloxane consisting of units (II) in which the residue Z^(o)represents a C₂-C₆ alkenyl group and where x₁ is at least equal to 1,optionally combined with units (I′), and on the other hand on a linear,branched or crosslinked hydrogenopolysiloxane consisting of units (II′)in which the residue Z^(o) then represents a hydrogen atom and where x₁is at least equal to 1, optionally combined with units (I′).

The bicomponent or monocomponent polyorganosiloxane compositionscrosslinking at room temperature (RTV) by polycondensation reactionsunder the action of moisture, generally in the presence of a metalcatalyst, for example a tin compound are described for example for themonocomponent compositions in patents U.S. Pat. Nos. 3,065,194,3,542,901, 3,779,986, 4,417,042, and in patent FR-A-2 638 752, and forthe bicomponent compositions in patents U.S. Pat. Nos. 3,678,002,3,888,815, 3,933,729 and 4,064,096. The polyorganosiloxanes enteringinto these compositions are in general linear, branched or crosslinkedpolysiloxanes consisting of units (II′) in which the residue Z^(o) is ahydroxyl group or a hydrolysable group or atom and where x₁ is at leastequal to 1, with the possibility of having at least one residue Z^(o)which is equal to a hydroxyl group or to an atom or to a hydrolysablegroup and at least one residue Z^(o) which is equal to an alkenyl groupwhen x₁ is equal to 2 or 3, said units (II′) being optionally combinedwith units (I′). Parallel compositions may contain in addition acrosslinking agent which is in particular a silane carrying at leastthree hydrolysable groups such as for example a silicate, analkyltrialkoxysilane or an aminoalkyltrialkoxysilane.

These RTV polyorganosiloxane compositions which crosslink bypolyaddition or polycondensation reactions advantageously have aviscosity at 25° C. at most equal to 100 000 mPa·s and preferably ofbetween 10 and 50 000 mPa·s.

It is possible to use RTV compositions which crosslink at roomtemperature by polyaddition or polycondensation reactions, having aviscosity at 25° C. greater than 100 000 mPa·s, such as that situated inthe interval ranging from a value greater than 100 000 mPa·s to 300 000mPa·s; this feature is recommended when it is desired to prepare chargedcurable compositions in which the filler(s) used has (have) a tendencyto separate by sedimentation.

It is also possible to use compositions which crosslink with heat bypolyaddition reactions and more precisely so-called polyaddition HVEtype compositions having a viscosity at 25° C. at least equal to 500 000mPa·s and preferably of between 1 million mPa·s and 10 million mPa·s andeven more.

This may also include compositions curable at high temperature under theaction of organic peroxides such as 2,4-dichlorobenzoyl peroxide,benzoyl peroxide, t-butyl perbenzoate, cumyl peroxide, di-t-butylperoxide. The polyorganosiloxane or gum entering into such compositions(termed simply of the HVE type) then essentially consists of siloxylunits (I′), optionally combined with units (II′) in which the Z^(o)residue represents a C₂-C₆ alkenyl group and where x is equal to 1. SuchHVEs are for example described in patents U.S. Pat. Nos. 3,142,655,3,821,140, 3,836,489 and 3,839,266). These compositions advantageouslyhave a viscosity at 25° C. at least equal to 1 million mPa·s andpreferably of between 2 million and 10 million mPa·s and even more.

Other polyorganosiloxane compositions which can be varnished with thesilicone varnish composition according to the invention are those,monocomponent or bicomponent, which crosslink with heat by polyadditionreactions, called LSR compositions. These compositions correspond to thedefinitions given above in relation to the preferred compositions calledRTV, except as regards their viscosity which is situated, this time, inthe interval ranging from a value greater than 100 000 mPa·s to 500 000mPa·s.

Without this being limiting, the elastomeric silicone coatings ontowhich the varnish according to the invention may be applied in order toreduce their coefficient of friction, are more especially coatingsobtained from compositions of silicone elastomers which are coldvulcanizable RTV, in particular of the bicomponent type (RTV 2), bypolyaddition.

In a more preferred manner still, these silicone elastomer layers forcoating are used in the coating of textile fabric for inflatable bagsfor the personal protection of the occupants of vehicles (air bag).

It results therefrom that another subject of the invention consists ofthe varnish support as defined above, characterized in that it isintended to be used for the manufacture of inflatable bags for thepersonal protection of the occupants of vehicles.

According to another of these subjects, the present invention alsorelates to an inflatable bag for the personal protection of theoccupants of vehicles, characterized in that it is produced fromabovesaid support.

In the context of this air bag application, the RTV elastomeric siliconecoatings more particularly in question may be those belonging to thefour groups (i) (ii) (iii) and (iv) as defined below.

-   -   (i) silicone elastomer composition for coating of the RTV 2 type        comprising at least one POS I of the SiVi type, at least one POS        II of the SiH type, a platinum-based hydrosilylation catalyst        III, an adhesion promoter IV comprising at least one alkoxylated        organosilane IV.1 containing per molecule at least one vinyl        (vinyltrimethoxysilane) group, at least one        organosilicon-containing compound IV.2 comprising at least one        epoxy radical (3-glycidoxypropyltrimethoxysilane (GLYMO) and at        least one chelate IV.3 of a metal M and/or a metal alkoxide        (butyl titanate).    -    These polyaddition RTV silicone coatings for air bags are        described in French patent No. 2 719 598 (No. 94 05 652).    -   (ii) Polyaddition RTV 2 silicone elastomer obtained from a        composition comprising POSs type I SiVi and POSs type II SiH, as        well as a particulate filler obtained by treatment using a        compatibility-promoting agent introduced into the preparation        medium: on the one hand, before and/or substantially        simultaneously with the bringing into contact with a portion of        the silicone oil used with a portion of the particulate filler,        this introduction of compatibility-promoting agent being carried        out once or several times for a fraction of        compatibility-promoting agent represents at most 8% by dry        weight of the total particulate filler;    -    and, on the other hand, after this POS/filler bringing into        contact. The compatibility-promoting agent is        hexamethyldisilasane HMDZ.    -    The oil SiVi is an α,ω-divinyl-containing polydimethylsiloxane        and the oil II SiH is an α,ω-dihydrogeno polydimethylsiloxane        and a polyhydrogeno oil PDMS. This RTV elastomer        composition (ii) which can be crosslinked by polyaddition and        comprises a particulate charge made compatible in a particular        manner with HMDZ, is described in detail in French patent        application No. 97 08 171.    -   (iii) RTV silicone elastomer coating crosslinked by        polycondensation and comprising a silicic particulate filler        treated using a compatibility-promoting agent introduced into        the preparation medium,    -    on the one hand, before and/or substantially simultaneously        with the bringing into contact of a portion of the silicone oil        used with a portion of the particulate filler, this introduction        of compatibility-promoting agent being carried out once or        several times for a fraction of compatibility-promoting agent        represents at most 8% by dry weight of the total particulate        filler;    -    and, on the other hand, after this POS/filler bringing into        contact. The compatibility-promoting agent is        hexamethyldisilasane HMDZ.    -    These polycondensation RTV silicone coatings whose filler is        treated in a specific manner with HMDZ, which are intended in        particular for the coating of textile fabric for air bags, are        described in French patent application No. 98 16 467 describing        compositions comprising:    -    1—at least one linear reactive POS carrying at each chain end        at least two condensable groups (other than OH) or which is        hydrolysable, or a single hydroxyl group,    -    2—optionally at least one linear nonreactive POS carrying no        condensable group, which is hydrolysable or a hydroxyl group,    -    3—optionally water,    -    4—a particulate reinforcing filler based on silica treated with        a compatibility-promoting agent (hexamethyldisilazane), this        compatibility-promoting agent being introduced into the        composition before and after the incorporation of the        reinforcing filler into at least a portion of the silicone        material, the fraction of compatibility-promoting agent        introduced before the incorporation of the filler representing        from 8 to 30% by weight of the reinforcing filler used.    -    (POS 1=polydimethylsiloxaneα,ω-(CH₃)₃SiO_(1/2); POS        2=polydimethylsiloxaneα,ω-(CH₃)₂OHSiO_(1/2));    -   (iv) RTV silicone elastomer coating crosslinked by polyaddition        and obtained from a coating composition comprising:        -   (1) at least one polyorganosiloxane having, per molecule, at            least two C₂-C₆ alkenyl groups linked to the silicon (e.g.            PolyDimethylSiloxane (PDMS-α,ω vinylated);        -   (2) at least one polyorganosiloxane having, per molecule, at            least two hydrogen atoms linked to the silicon (e.g. PDMS            α,ω dihydrogeno and PDMS polyhydrogeno),        -   (3) a catalytically effective quantity of at least one            catalyst composed of at least one metal belonging to the            platinum group (e.g.: KARSTEDT 10% Pt)        -   (4) a ternary adhesion promoter consisting of:            -   (4.1.) at least one alkoxylated organosilane containing,                per molecule, at least one C₃-C₆ alkenyl group (e.g.:                γ-methacryloxypropylated trimethoxysilane)            -   (4.2.) at least one organosilicon-containing compound                comprising at least one epoxy radical (e.g.:                γ-glycidoxypropyl trimethoxysilane)            -   (4.3) at least one metal M chelate and/or one metal                alkoxide of general formula: M(OJ)n, with n=valency            -    of M and J=linear or branched C₁-C₈ alkyl,            -    M being chosen from the group formed by: Ti, Zr, Ge,                Li, Mn, Fe, Al and Mg (e.g.: butyl titanate).        -   (5) a reinforcing siliceous filler treated in situ with a            compatibility-promoting agent (e.g.: HMDZ) in the presence            of polyorganosiloxane (1),        -   (6) a so-called extending polyorganosiloxane having terminal            siloxyl units with hydrogeno functional groups (e.g. PDMS            α,ω-hydrogeno—RHODORSIL® 620 from RHODIA CHIMIE)        -   (7) optionally a neutralizing agent,        -   (8) optionally a crosslinking inhibitor and/or other            additive(s) in use in this type of compositions (e.g.:            ethynylcyclohexanol).        -   (9) and optionally expanded or expandable inorganic hollow            microspherical fillers, in which method a suspension of            reinforcing siliceous filler is prepared by bringing this            siliceous filler into contact with the            compatibility-promoting agent and polyorganosiloxane (1),            which constitutes the in situ treatment of the filler.

All these crosslinkable and/or crosslinked RTV elastomeric siliconecompositions are prepared in a conventional manner (bicomponentprecursor system) and are described for example in French patent No. 2719 598, as regards the RTVs (iv).

Once the bicomponent impasting has been carried out, it is applied tothe support by any appropriate means of coating, for example a scraperor a roller. The crosslinking of the layer coated onto the support maybe caused, for example, by the thermal route and/or by UV radiation.

The support thus coated may be a flexible material such as, for example,an advantageously woven fibrous support made of synthetic fibers, e.g.polyester or polyamide. Such coated tissues may be used for themanufacture, by sewing, of an inflatable bag for an automobile (airbag).

Once the support has been coated with the crosslinked RTV elastomerlayer, the antifriction silicon varnish is applied in accordance withthe invention and then the crosslinking of said varnish is carried outby exposure to actinic radiation or to electron beams.

In addition to the textile supports coated with silicone, theantifriction varnish according to the invention may be applied:

-   -   to plastic films (e.g. made of polyester) such as thermal        transfer ribbons for printers of the same name,    -   or to protective wrapping plastic films (e.g. made of        polyethylene or of polypropylene).

In these two applications, the antifriction varnish according to theinvention will promote the sliding of at least one of the surfaces ofthe plastic film, it being possible for this surface to be coated withat least one silicone layer.

The examples which follow describe:

-   -   the preparation of the antifriction varnish compositions        according to the invention,    -   the application of the latter:        -   to fabric supports coated with a polyaddition RTV            crosslinked silicone elastomer,        -   to thermal transfer ribbons comprising a polyester film of a            few microns,        -   and to polyethylene wrapping films.    -   and the evaluation of the samples thus obtained in terms of        coefficient of friction,

EXAMPLES

In the examples which follow, the production of formulations which canbe directly exploited for the production of UV varnish for air bags isdescribed.

Examples 1 to 14

Photocrosslinkable varnish formulations are prepared from the followingpolymers:

A/

A₁/SILCOLEASE® UV POLY201: x=CH₃; a=70; b=7

A₂/SILCOLEASE® UV POLY201; x=CH₃; a=444; b=35

C₂/

Photoinitiator SILCOLEASE® UV CATA 211

Photoinitiator RHODORSIL® Photoinitiator 2074

G2/Aerosil silica having a specific surface area of 300 m²/g fromDEGUSSA treated with octamethylcyclotetrasiloxane Red 22/red pigmentmarketed by SUN CHEMICAL.

These compositions are then applied with the aid of coating barsnumbered differently from 0 to 6 in order to deposit from 1 to 20 g/m²on a rectangle of polyamide fabric comprising a silicone elastomer atthe surface of the crosslinked polyaddition RTV type (140 g/m²).

40 kg of an α,ω-divinylated silicone oil having a viscosity of 1.5 Pa·swith a titer of 0.1 meq of vinyl (Vi) per gram of oil, 0.24 kg ofpotable water and 0.24 kg of hexamethyldisilazane are introduced into a100 l arm mixer. After homogenization, 13.9 kg of a pyrogenic silicacharacterized by its specific surface area of 200 m²/g are added inportions over roughly 2 hours. After about 1 hour of mixing, 2.27 kg ofhexamethyldisilazane are added over roughly 1 hour. 2 hours later, aheating phase is started during which the mixture is placed under anitrogen stream (30 m³/h); the heating continues until about 140° C. isreached, a plateau temperature which is maintained for 2 hours in orderto remove the volatile materials from the composition. The suspension isthen allowed to cool.

Starting with this suspension, a portion A and a portion B areformulated in appropriate reactors.

Portion A contains:

-   -   320 g of the suspension,    -   111 g of an α,ω-divinylated oil having a viscosity of 100 Pa.s        which has a titer of 0.03 meq Vi per gram of oil,    -   35 g of ground quartz having a mean particle size (d50) close to        2.5 μm,    -   12 g of a polyhydrogeno oil having a viscosity of 0.3 Pa.s which        has a titer of 1.6 meq SiH per gram of oil,    -   12 g of an α,ω-dihydrogeno oil which has a titer of 1.9 meq SiH        per gram of oil,    -   5 g of γ-methacryloxypropyl trimethoxysilane,    -   5 g of γ-glycidoxypropyl trimethoxysilane,    -   0.7 g of ethynylcyclohexano.

Portion B contains:

-   -   480 g of the suspension    -   20 g of butyl orthotitanate    -   1.1 g of a Karstedt catalyst containing a dose of 10% platinum.

100 parts by weight of A and 10 parts by weight of B are then mixed.

The crosslinking is carried out on a laboratory conveyor by exposure ata defined speed under two electrode lamps of 200 W/cm.

Depending on the experimental conditions, one or two lamps are inoperation. The lamps are traditional lamps with a spectrum of emissionof mercury or of mercury doped for example with iron or with gallium orwith lead or the like.

The coefficients of friction are measured after exposure with the aid ofa 200 g block linked to a dynamometer which can exact a force of 10N inorder to move the block. To carry out the measurement, the tip of thefabric is installed on the block on the surface coated with siliconevarnish on the glass side. A blank is carried out with a fabric coatedwith varnish-free crosslinked RTV. All the results obtained for examples1 to 14 are assembled in the following table.

Photocrosslinkable compositions for the varnishing of air bags C 1 2 3 45 6 7 8 9 10 11 12 13 14 A₁ parts 0 100 90 0 0 0 0 0 0 0 50 70 0 20 20A₂ parts 0 0 0 0 0 0 0 0 0 0 0 0 50 0 0 D₁ parts 0 0 0 100 90 0 0 0 4545 50 30 50 72 72 D₂ parts 0 0 0 0 0 100 100 90 45 45 0 0 0 0 0 C₂ parts0 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 G₂ parts 0 010 0 10 0 0 10 10 10 0 0 0 8 8 Red22 parts 0 0 0 0 0 0 0 0 0 0 0 0 0 00.4 Hg lamp 200 0 1 1 1 1 1 1 1 0 0 1 1 1 2 1 W/cm Hg/Ca lamp 0 1 1 1 10 0 0 0 0 1 1 1 0 0 200 W/cm Hg/Ca lamp 80 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0W/cm Speed m/min 0 15 15 15 15 5 5 5 5 5 5 15 15 10 5 Deposit g/m² 0 4 95 7.8 1 6.9 8 4.5 1.8 9 6.4 5.6 6.4 5 Coef. fric. Ks 3.2 4 4 2 0.6 2.61.5 0.3 0.3 0.5 1.1 4.5 0.5 0.8

The best performances are obtained with the B₂/type polymers in thepresence of a silica-based filler. The results vary according to theirradiation conditions; in particular, the values obtained at low power,examples 8 and 9, are of great interest. The A/type polymer may be addedwithout affecting the results of Ks too much.

Example 15

Trials for the continuous application of the formula described inexample 13 are carried out on a machine representative of an industrialequipment (pilot ROTOMEC) at 25 m/min on a width of fabric coated withRTV of 30 cm.

The irradiation conditions are obtained with a lamp from the companyFusion with an “H⁺” type bulb having a power of 80 W/cm.

3 deposits are made.

The coefficients of friction are then measured on glass.

The following are obtained:

-   3.5 g/m² of varnish corresponds to a Ks=1.4-   6.0 g/m² of varnish corresponds to a Ks=0.8-   9.0 g/m² of varnish corresponds to a Ks=0.5

The expected performances are indeed found for this formulation at acomparable deposit.

Example 16

Preparation of B₂

The synthesis is carried out in two steps from an α-ω-trimethylsilylpolymethylhydrogenodimethylsiloxane oil. The synthesis is carried outaccording to the reaction scheme described below.

50 g of toluene and 28.8 mg of a complex of platinum having theoxidation level zero complexed with divinyltetramethyldisiloxane at11.5% platinum, that is 3.31 mg of platinum are loaded into athree-necked reactor provided with a central stirring paddle and with acapacity of 1 liter. 200 g of the siloxane polymer hydrogenated at0.374%, that is 0.748 mol H, mixed with 70.97 g of vinyltriethoxysilane(that is 0.372 mol) at 25° C. are then poured in over 120 minutes andthen the reaction mass is heated at 60° C. for two hours. The rate ofconversion of the SiH units is 50%, that is 0.372 mol.

The freshly distilled vinylcyclohexene oxide is then added at the rateof 57 g (0.459 mol) and the reaction temperature is brought to 80° C.for three hours and 40 mg of the platinum complex are added during thelast hour.

The medium is allowed to return to room temperature. The rate ofconversion of the SiH units is 98.3%. The medium is heated to 100° C.and 40 mg of additional platinum complex are added and then the mediumis left at 100° C. for three hours. The rate of conversion of the SiHunits is 99.8%. The reaction mass is drawn off into a 500 mlround-bottomed flask (360.2 g) and 0.3 g of 2,2-thiodiethanol is addedand then a vacuum is created and the toluene is carried away by flushingwith argon at 97° C. into the reaction mass and 30 to 40° C. at the topof the column. After stopping the vacuum and cooling to 40° C., 1.47 gof polyvinylpyridine (Reillex) and 1.53 g of hydrogen peroxide (Prolabo)are added.

The medium is heated at 80° C. for two hours and 4.72 g of magnesiumsulfate are added to the reaction mass. Filtration is then carried outon a carton of the oil obtained decolorized and the total mass yield ofthe synthesis is 86%, that is 272 g.

The viscosity of the oil is 55 mm²/s.

The number-average molecular mass is about 1300 determined by gelpermeation chromatography.

The ²⁹Si NMR makes it possible to identify and quantify the units.

The reference is tetramethylsilane.

-   Me₃SiO_(1/2) δ32 7 ppm that is two units-   Me₂SiO_(2/2) and MeRSiO δ=22 ppm that is 13 units-   R′Si(OEt)₃ δ=−45/−46 ppm that is two units

The ¹H NMR completes the analysis of the product and confirms theexpected structure of the polymer D₂.

Example 17

Example of formulation which makes it possible to produce the formulasdescribed in example 1 to 14

Example 17.1

The formula described in example 1 is produced.

100 parts of A₁ Silcolease UV® POLY200 having a viscosity of 350 mPa·sare mixed, with vigorous mechanical stirring for a quarter of an hour atroom temperature (IKA20 stirrer equipped with a triple-paddle rod) in alight-tight high-density polyethylene bottle, with 2.5 parts of C₂, thatis a dilution in isopropanol at 18% of photoinitiator Rhodorsil®Photoinitiator 2074.

Example 17.2

The formula described in example 2 is produced.

90 parts of A₁ Silcolease UV® POLY200 A₁ having a viscosity of 350 mPa·sare mixed, with vigorous mechanical stirring for half an hour at roomtemperature (IKA20 stirrer equipped with a triple paddle rod) in alight-tight high-density polyethylene bottle, with 10 parts of silicaG₂. When the mixture is well homogeneous and the silica is incorporated,2.5 parts of C₂ are then added, that is a dilution in isopropanol at 18%of photoinitiator Rhodorsil® Photoinitiator 2074 and the medium isvigorously stirred for an additional fifteen minutes.

Example 17.3

The formula described in example 3 is produced.

100 parts of triethoxysilyl silane with epoxycyclohexyl functionality B₁having a viscosity of 10 mPa·s are mixed, with vigorous mechanicalstirring for a quarter of an hour at room temperature (IKA20 stirrerequipped with a triple-paddle rod) in a light-tight high-densitypolyethylene bottle, with 2.5 parts of C₂, that is a dilution inisopropanol at 18% of photoinitiator Rhodorsil® Photoinitiator 2074.

Example 17.4

The formula described in example 4 is produced.

90 parts of Silane B₁ having a viscosity of 10 mPa·s are mixed, withvigorous mechanical stirring for a half an hour at room temperature(IKA20 stirrer equipped with a triple paddle rod) in a light-tighthigh-density polyethylene bottle, with 10 parts of silica G₂. When themixture is very homogeneous and the silica is incorporated, 2.5 parts ofC₂ are then added, that is a dilution in isopropanol at 18% ofphotoinitiator Rhodorsil® Photoinitiator 2074 and the medium isvigorously stirred for an additional fifteen minutes.

Example 17.5 and 17.6

The formula described in examples 5 and 6 is produced.

100 parts of polymer B₂ having a viscosity of 55 mPa·s whose synthesishas just been described exp 17 are mixed, with vigorous mechanicalstirring for a quarter of an hour at room temperature (IKA20 stirrerequipped with a triple paddle rod) in a light-tight high-densitypolyethylene bottle, with 2.5 parts of C₂ that is a dilution inisopropanol at 18% of photoinitiator Rhodorsil® Photoinitiator 2074.

Example 17.7

The formula described in example 7 is produced.

90 parts of polymer B₂ having a viscosity of 55 mPa·s whose synthesishas just been described exp.17 are mixed, with vigorous mechanicalstirring for a half an hour at room temperature (IKA20 stirrer equippedwith a triple paddle rod) in a light-tight high-density polyethylenebottle, with 10 parts of silica G₂. When the mixture is very homogeneousand the silica is incorporated, 2.5 parts of C₂ are then added, that isa dilution in isopropanol at 18% of photoinitiator Rhodorsil®Photoinitiator 2074 and the mixture is vigorously stirred for anadditional fifteen minutes.

Example 17.8 and 17.9

The formula described in examples 8 and 9 is produced.

45 parts of silane B₁ and 45 parts of polymer B₂ having a viscosity of55 mPa·s whose synthesis has just been described exp.17 are mixed, withvigorous mechanical stirring for a half an hour at room temperature(IKA20 stirrer equipped with a triple paddle rod) in a light-tighthigh-density polyethylene bottle, with 10 parts of silica G₂. When themixture is well homogeneous and the silica is incorporated, 2.5 parts ofC₂ are then added, that is a dilution in isopropanol at 18% ofphotoinitiator Rhodorsil® Photoinitiator 2074 and the medium isvigorously stirred for an additional fifteen minutes.

Example 17.10

The formula described in example 10 is produced.

50 parts of silane B₁ and 50 parts of polymer A₁ having a viscosity of350 mPa·s are mixed, with vigorous mechanical stirring, for a quarter ofan hour at room temperature (IKA20 stirrer provided with a triple paddlerod) in a light-tight high-density polyethylene bottle.

2.5 parts of C₂ that is a dilution in isopropanol at 18% ofphotoinitiator Rhodorsil® Photoinitiator 2074 are added and the mediumis vigorously stirred for an additional five minutes.

Example 17.11

The formula described in example 11 is produced.

30 parts of silane B₁ and 70 parts of polymer A₁ having a viscosity of350 mPa·s are mixed, with vigorous mechanical stirring, for a quarter ofan hour at room temperature (IKA20 stirrer provided with a triple paddlerod) in a light-tight high-density polyethylene bottle.

2.5 parts of C₂ that is a dilution in isopropanol at 18% ofphotoinitiator Rhodorsil® Photoinitiator 2074 are added and the mediumis vigorously stirred for an additional five minutes.

Example 17.12

The formula described in example 12 is produced.

50 parts of silane B₁ and 50 parts of polymer A₂ having a viscosity of5000 mPa·s are mixed, with vigorous mechanical stirring, for half anhour at room temperature (IKA20 stirrer provided with a triple paddlerod) in a light-tight high-density polyethylene bottle.

2.5 parts of C₂ that is a dilution in isopropanol at 18% ofphotoinitiator Rhodorsil® Photoinitiator 2074 are added and the mediumis vigorously stirred for an additional five minutes.

Example 17.13

The formula described in example 13 is produced.

72 parts of silane B₁ and 20 parts of SILCOLEASE® UV POLY200 A₁ having aviscosity of 350 mPa·s whose synthesis has just been described exp.17are mixed, with vigorous mechanical stirring for a half an hour at roomtemperature (IKA20 stirrer equipped with a triple paddle rod) in alight-tight high-density polyethylene bottle, with 10 parts of silicaG₂. When the mixture is very homogeneous and the silica is incorporated,2.5 parts of C₂ are then added, that is a dilution in isopropanol at 18%of photoinitiator Rhodorsil® Photoinitiator 2074 and the medium isvigorously stirred for an additional fifteen minutes.

Example 17.14

The formula described in example 14 is produced.

72 parts of silane B₁ and 20 parts of SILCOLEASE® UV POLY200 A₁ having aviscosity of 350 mPa·s whose synthesis has just been described exp.17are mixed, with vigorous mechanical stirring for a half an hour at roomtemperature (IKA20 stirrer equipped with a triple paddle rod) in alight-tight high-density polyethylene bottle, with 10 parts of silicaG₂. When the mixture is very homogeneous and the silica is incorporated,0.4 parts of red pigment Red22 marketed by Sun chemical are then addedand the medium is vigorously stirred until perfect dilution of thepigment is obtained which results in the production of a transparentlight red formulation. 2.5 parts of C₂ are then added, that is adilution in isopropanol at 18% of photoinitiator Rhodorsil®Photoinitiator 2074 and the medium is vigorously stirred for anadditional fifteen minutes.

Example 18

Thermal transfer ribbons are used for example in the printing of labels.They are used in printers whose printing speed varies between 150 and300 mm/s. It is very important for the printing head (flat orwedge-like) which strikes the other side of the surface containing theink (waxes or resins) to be able to slide over this surface at hightemperature of between 100 and 200° C.

A very thin protective coating of between 0.1 and 1 micrometer isgenerally used to protect the surface of the film and improve the impactof the printing head without deforming the transfer of the ink onto theapplied support.

The plastic film used to transfer the ink is based on very thinpolyester having a thickness of a few microns.

A good measurement of the quality of the protective coating is made bythe sliding capacity of this coating.

The coefficient of friction is then measured after exposure with the aidof a 200 g block linked to a dynamometer which can exert a force of 10Nin order to move the block.

To make the measurement, the polyester film coated with a protectivecoating layer based on photocrosslinked silicone preferably of less than1 micrometer is installed. A blank is made with the polyester filmcontaining no silicone.

The results obtained are assembled in the following table forcompositions containing various portions of:

-   A₁/SILCOLEASE® UV POLY200-   A₂/SILCOLEASE® UV POLY201

in isopropanolic solution at 18%.

G₂/Aerosil silica 300 m²/g

The polyester films are coated with silicone on a 5-roll head, at aspeed of 50 m/min (0.5 g/m²) and then photocrosslinked with a 120 W/cmlamp.

The drag ratio or dynamic friction coefficient values obtained asdescribed above are presented in the table below.

Silicone formulations: Control 1′ 2′ 3′ 4′ 5′ A₁ parts 0 100 100 75 2260 D₁ parts 0 0 0 25 75 35 C₂ parts 0 2.5 3 2.5 2.5 2.5 G₂ parts 0 0 0 03 5 Coef. fric. Kd 0.3 3 1 0.33 0.25 0.4

Example 19

It is also possible to seek to obtain plastic films mainly based onpolyethylene or polypropylene intended for wrapping in order to protectmarket values. In this case, it is possible to seek to have atop-varnishing based on silicone in order to retain the anti-adhesionproperties.

This type of coating is also required to retain a slipperiness at leastequivalent to the starting plastic film imprinted or otherwise.

Trials were carried out for the application of silicone layers at lessthan 1 micrometer to 50 m/min to coronna-treated polyethylene film(electrical discharge which makes it possible to increase the surfacetension of the film and to ensure good sticking of thephotocrosslinkable silicone to this surface). The silicone isphotocrosslinked in the presence of a 120 W/cm mercury lamp. Twosupports were used. One virgin support, and one support printed with ablue cationic flexo® ink 3 μm thick.

In both cases, 0.5 g/m² of silicone of the formulation 5′ is appliedaccording to example 18 described above.

In both cases, a perfectly crosslinked silicone layer is obtained whosecoefficient of friction is in the region of 0.4.

It is possible to apply the silicone compositions premixed beforehand inthe form of monocomponent compositions or to prepare the siliconephotoinitiator mixture at the last moment.

1. A varnish support having antifriction properties, said supportcomprising a substrate coated on at least one of its surfaces with atleast one layer of silicone elastomer which is crosslinked or which isat least partially crosslinked, said layer of silicone elastomer coatedwith an antifriction varnish obtained from a silicone compositioncomprising at least one polyorganosiloxane (POS) which is crosslinked bymeans of crosslinking functional groups (CFG) by the cationic and/orfree-radical route and an effective quantity of a cationic initiatorsystem comprising, as thermal initiator and/or photoinitiator, a productchosen from the onium salts of an element of groups 15 to 17 of thePeriodic Table or the salts of an organometallic complex of an elementof groups 4 to 10 of the Periodic Table, whose cationic entity isselected from: 1) the onium salts of formula (I):[(R¹)_(n)-A-(R²)_(m)]⁺  (I) in which formula: A represents an element ofgroups 15 to 17 of the Periodic Table; R¹ represents a carbocyclic orheterocyclic C₆-C₂₀ aryl radical, it being possible for saidheterocyclic radical to contain, as heteroelements, nitrogen or sulfur;R² represents R¹ or a linear or branched C₁-C₃₀ alkyl or alkenylradical, said radicals R¹ and R² being optionally substituted with aC₁-C₂₅ alkoxy, C₁-C₂₅ alkyl, nitro, chloro, brorao, cyano, carboxyl,ester or mercapto group; n is an integer ranging from 1 to v+1, v beingthe valency of the element A; m is an integer ranging from 0 to v 1 withn+m =v+1; 2) oxoisothiochromanium salts; 3) sulfonium salts in which thecationic entity comprises: 3-1) at least one polysulfonium species offormula (III.1):

in which: the symbols Ar¹, which may be mutually identical or different,each represent a monovalent phenyl or naphthyl radical optionallysubstituted with one or more radicals chosen from: a linear or branchedC₁-C₁₂ alkyl radical, a linear or branched C₁-C₂ alkoxy radical, ahalogen atom, an —OH group, a —COOH group, an ester group —COO-alkylwhere the alkyl portion is a linear or branched C₁-C₁₂ residue, and agroup of formula —Y⁴—Ar² where the symbols Y⁴ and Ar² have the meaningsgiven just below; the symbols Ar², which may be mutually identical ordifferent, or identical to A¹, each represent a monovalent phenyl ornaphthyl radical optionally substituted with one or more radicals chosenfrom: a linear or branched C₁-C₁₂ alkyl radical, a linear or branchedC₁-C₁₂ alkoxy radical, a halogen atom, an —OH group, a —COOH group, anester group —COO-alkyl where the alkyl portion is a linear or branchedC₁-C₁₂ residue, the symbols Ar³, which may be mutually identical ordifferent, each represent a divalent phenylene or naphthylene radicaloptionally substituted with one or more radicals chosen from: a linearor branched C₁-C₁₂ alkyl radical, a linear or branched C₁-C₁₂ alkoxyradical, a halogen atom, an —OH group, a —COOH group, an ester group—COO-alkyl where the alkyl portion is a linear or branched C₁-C₁₂residue, t is an integer equal to 0 or 1, with the additional conditionsaccording to which: a) when t=0, the symbol Y is then a monovalentradical Y¹ representing the group of formula:

where the symbols Ar¹ and Ar² have the meanings given above, b) whent=1: b1) on the one hand, the symbol Y is then a divalent radical havingthe following meanings Y² to Y⁴: Y²: a group of formula:

 where the symbol Ar² has the meanings given above, Y³: a single valencybond, Y⁴: a divalent residue chosen from:

 a linear or branched C₁-C₁₂ alkylene residue, and a residue of formula—Si(CH₃)₂O—, b2) on the other hand, only in the case where the symbol Yrepresents Y³ or Y⁴, the radicals Ar¹ and Ar² (terminal) possess, inaddition to the meanings given above, the possibility of being linked toeach other by the residue Y′ consisting of Y′¹ a single valency bond orof Y′² a divalent residue chosen from the residues cited in thedefinition of Y⁴, which is seated between the carbon atoms, facing oneanother, situated on each aromatic ring at the ortho position withrespect to the carbon atom directly linked to the cation S⁺; 3-2) and/orat least one mono-sulfonium species possessing a single cationic centerS⁺ per mol of cation and consisting of species of formula (III.2):

in which Ar¹ and Ar² have the meanings given above in formula (III.1),including the possibility of directly linking to one another only one ofthe radicals Ar¹ to Ar² in the manner indicated above in the definitionof the additional condition which applies when t=1 in formula (III.1),involving the residue Y′; 4) the organometallic salts of formula (IV):(L¹L²L³M)^(+q)  (IV) in which formula: M represents a metal of group 4to 10 of the Periodic Table; L¹ represents a ligand linked to the metalM by π electrons, a ligand chosen from the ligands η³-alkyl,η⁵-cyclopentadienyl and η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η6-benzene ligands andthe compounds having from 2 to 4 fused rings each ring being capable ofcontributing to the valency layer of the metal N by 3 to 8 π electrons;L² represents a ligand linked to the metal M by π electrons, a ligandchosen from the ligands η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η⁶-benzene ligands andthe compounds having from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M by 6 or 7 π electrons;L³ represents from 0 to 3 identical or different ligands linked to themetal M by σ electrons, ligand(s) chosen from CO and NO₂ ⁺; the totalelectron charge q of the complex to which L¹, L² and L³ contribute andthe ionic charge of the metal M being positive and equal to 1 or 2; theanionic entity having the formula: [X¹X² _(a)R_(b)]⁻ in which formula: aand b are integers ranging, for a, from 0 to 6 and, for b, from 0 to 6with a+b≧2; the symbols X¹ represent elements chosen from groups 3A, 4A,5A of the Periodic Table; the symbols X² represent: a halogen atom witha=0 to 3, an OH functional group with a=0 to 2; the symbols R areidentical or different and represent: a phenyl radical substituted withat least one electron-attracting group, and/or with at least 2 halogenatoms, and this being when the cationic entity is an onium of an elementof groups 15 to 17 of the Periodic Table, a phenyl radical substitutedwith at least one electron-attracting atom or one electron-attractinggroup, and this being when the cationic entity is an organo-metalliccomplex of an element of groups 4 to 10 of the Periodic Table, an arylradical containing at least two aromatic nuclei, optionally substitutedwith at least one element or one electron-attracting group, regardlessof the cationic entity; wherein said POS carrying CFG are epoxysiliconesand/or vinyl ether silicones which are: 1) either linear and consist ofunits of formula (II-1), ending with units of formula (II-2), 2) orcyclic and consisting of units of formula (II-1):

in which formulae: the symbols R¹⁶ are similar or different andrepresent either a linear or branched C₁-C₆ alkyl radical optionallysubstituted with one or more halogens, or an optionally substitutedC₅-C₈ cycloalkyl radical, or an aryl or aralkyl radical optionallysubstituted with halogens and/or alkoxyls, the symbols Z are similar ordifferent and represent either the radical R¹⁶, or a CFG groupcorresponding to an epoxide or vinyl ether residue linked to the siliconby means of a divalent radical containing from 2 to 20 carbon atomsoptionally comprising a heteroatom, at least one of the symbols Zcorresponding to a CFG group, said composition comprising, in addition,a silane substituted with CFG and hydrolyzable secondary functionalgroups (SFG) and having the formula


2. The varnish support of claim 1, wherein said POS carrying CFG areepoxysilicones of the following formulae (A-I) or (A-II):

with X+CH₃; phenyl; cycloalkyl; C₁-C₁₈ alkyl; alkenyl; —OH; H;CH₂—CH₂—CH₂—OH; CH₂—CH₂—CF₃; or —(CH₂)_(n)—CF₃, n=1 to 20;

a₁, a₂ and b₁, b₂ being defined as below in these formulae (A-I) and(A-II)1≦a₁, a₂1≦b₁, b₂; a₂, b₂ being=0 in formula (A-II) to gave theepoxydized disiloxane (A-III).
 3. The varnish support of claim 1,wherein said composition further comprises: at least one organicreactive diluent chosen from organic resins of the epoxide and/or vinylether and/or oxethane type; optionally at least one organic or inorganicpigment; optionally a filler; optionally at least one photosensitizer.4. The varnish support of claim 1, wherein said at least one layer ofsilicone elastomer which is crosslinked or at least partiallycrosslinked, is chosen from the polyaddition or polycondensation RTVsilicones, and/or the peroxide HVE silicones, and/or the polyadditionLSR silicones.
 5. A method of coating a silicone composition as anantifriction varnish upon a support, comprising coating at least onesurface of a support with at least one layer of a silicone compositioncomprising at least one polyorganosiloxane (POS) which is crosslinked bymeans of crosslinking functional groups (CFG) by the cationic and/orfree-radical route and an effective quantity of a cationic initiatorsystem comprising, as thermal initiator and/or photoinitiator, a productchosen from the onium salts of an element of groups 15 to 17 of thePeriodic Table or the salts of an organometallic complex of an elementof groups 4 to 10 of the Periodic Table, whose cationic entity isselected from: 1) the onium salts of formula (I):[(R¹)_(n)-A-(R²)_(m)]⁺  (I) in which formula: A represents an element ofgroups 15 to 17 of the Periodic Table; R¹ represents a carbocyclic orheterocyclic C₆-C₂₀ aryl radical, it being possible for saidheterocyclic radical to contain, as heteroelements, nitrogen or sulfur;R2 represents R¹ or a linear or branched C₁-C₃₀ alkyl or alkenylradical, said radicals R¹ and R² being optionally substituted with aC₁-C₂₅ alkoxy, C₁-C₂₅ alkyl, nitro, chloro, bromo, cyano, carboxyl,ester or mercapto group; n is an integer ranging from 1 to v+1, v beingthe valency of the element A; m is an integer ranging from 0 to v−1 withn+m=v+1; 2) oxoisothiochromanium salts; 3) sulfonium salts in which thecationic entity comprises: 3-1) at least one polysulfonium species offormula (III.1):

in which: the symbols Ar¹, which may be mutually identical or different,each represent a monovalent phenyl or naphthyl radical optionallysubstituted with one or more radicals chosen from: a linear or branchedC₁-C₁₂ alkyl radical, a linear or branched C₁-C₁₂ alkoxy radical, ahalogen atom, an —OH group, a —COOH group, an ester group —COO-alkylwhere the alkyl portion is a linear or branched C₁-C₁₂ residue, and agroup of formula —Y⁴—Ar² where the symbols Y⁴ and Ar² have the meaningsgiven just below; the symbols Ar², which may be mutually identical ordifferent, or identical to Ar¹, each represent a monovalent phenyl ornaphthyl radical optionally substituted with one or more radicals chosenfrom: a linear or branched C₁-C₁₂ alkyl radical, a linear or branchedC₁-C₁₂ alkoxy radical, a halogen atom, an —OH group, a —COOH group, anester group —COO-alkyl where the alkyl portion is a linear or branchedC₁-C₁₂ residue, the symbols Ar³, which may be mutually identical ordifferent, each represent a divalent phenylene or naphthylene radicaloptionally substituted with one or more radicals chosen from: a linearor branched C₁-C₁₂, alkyl radical, a linear or branched C₁-C₁₂, alkoxyradical, a halogen atom, an OH group, a —COOH group, an ester group—COO-alkyl where the alkyl portion is a linear or branched C₁-C₁₂residue, t is an integer equal to 0 or 1, with the additional conditionsaccording to which: a) when t=0, the symbol Y is then a monovalentradical Y¹ representing the group of formula:

where the symbols Ar¹ and Ar² have the meanings given above, b) whent=1: b1) on the one hand, the symbol Y is then a divalent radical havingthe following meanings Y² to Y⁴: Y²: a group of formula:

where the symbol Ar² has the meanings given above, Y³: a single valencybond, Y⁴: a divalent residue chosen from:

a linear or branched C₁-C₁₂ alkylene residue, and a residue of formula—Si(CH₃)₂O—, b2) on the other hand, only in the case where the symbol Yrepresents Y³ or Y⁴, the radicals Ar¹ and Ar² (terminal) possess, inaddition to the meanings given above, the possibility of being linked toeach other by the residue Y′ consisting of Y′¹ a single valency bond orof Y′² a divalent residue chosen from the residues cited in thedefinition of Y⁴, which is seated between the carbon atoms, facing oneanother, situated on each aromatic ring at the ortho position withrespect to the carbon atom directly linked to the cation S⁺; 3-2) and/orat least one mono-sulfonium species possessing a single cationic centerS⁺ per mol of cation and consisting of species of formula (III.2):

in which Ar¹ and Ar² have the meanings given above in formula (III.1),including the possibility of directly linking to one another only one ofthe radicals Ar¹ to Ar² in the manner indicated above in the definitionof the additional condition which applies when t=1 in formula (III.1),involving the residue Y′; 4) the organometallic salts of formula (IV):(L¹L²L³M)^(+q)  (IV) in which formula: M represents a metal of group 4to 10 of the Periodic Table; L¹ represents a ligand linked to the metalM by π electrons, a ligand chosen from the ligands η³-alkyl,η⁵-cycloheptatrienyl and η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η⁶-benzene ligands andthe compounds having from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M by 3 to 8 π electrons;L² represents a ligand linked to the metal M by π electrons, a ligandchosen from the ligands η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η⁶-benzene ligands andthe compounds having from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M by 6 or 7 π electrons;L³ represents from 0 to 3 identical or different ligands linked to themetal M by σ electrons, ligand(s) chosen from CO and NO₂ ⁺; the totalelectron charge q of the complex to which L¹, L² and L³ contribute andthe ionic charge of the metal M being positive and equal to 1 or 2; theanionic entity having the formula: [X¹X² _(a)R_(b)]⁻ in which formula: aand b are integers ranging, for a, from 0 to 6 and, for b, from 0 to 6with a+b≧2; the symbols X¹ represent elements chosen from groups 3A, 4A,5A of the Periodic Table; the symbols X² represent: a halogen atom witha=0 to 3, an OH functional group with a=0 to 2; the symbols R areidentical or different and represent: a phenyl radical substituted withat least one electron-attracting group, and/or with at least 2 halogenatoms, and this being when the cationic entity is an onium of an elementof groups 15 to 17 of the Periodic Table, a phenyl radical substitutedwith at least one electron-attracting atom or one electron-attractinggroup, and this being when the cationic entity is an organo-metalliccomplex of an element of groups 4 to 10 of the Periodic Table, an arylradical containing at least two aromatic nuclei, optionally substitutedwith at least one element or one electron-attracting group, regardlessof the cationic entity; wherein said POS carrying CFG are epoxysiliconesand/or vinyl ether silicones which are; 2.) either linear and consist ofunits of formula (II-1), ending with units of formula (II-2), 2) orcyclic and consisting of units of formula (II-1):

in which formulae: the symbols R¹⁶ are similar or different andrepresent either a linear or branched C₁-C₆ alkyl radical optionallysubstituted with one or more halogens, or an optionally substitutedC₅-C₈ cycloalkyl radical, or an aryl or aralkyl radical optionallysubstituted with halogens and/or alkoxyls, the symbols Z are similar ordifferent and represent either the radical R₁₆, or a CFG croupcorresponding to an epoxide or vinyl ether residue linked to the siliconby means of a divalent radical containing from 2 to 20 carbon atomsoptionally comprising a heteroatom, at least one of the symbols Zcorresponding to a CFG group, said composition comprising, in addition,a silane substituted with CFG and hydrolyzable secondary functionalgroups (SFG) having the formula

exposing the surface thus coated to actinic radiation and/or to a beamof electrons and/or to heat, so as to cause the crosslinking of thesilicone composition and obtain an antifriction layer.
 6. The method ofclaim 5, wherein said POS carrying CFG are epoxysilicones of thefollowing formulae (A-I) or (A-II):

with X═CR₃; phenyl; cycloalkyl; C₁-C₁₈ alkyl; alkenyl; —OR; H;CH₂—CH₂—CH₂—OH; CH₂—CH₂—CF₃; or —(CH₂)_(n)—CF₃, n=1 to 20;

a₁, a₂ and b₁, b₂ being defined as below in these formulae (A-I) and(A^(II))1≦a₁, a₂ 1≦b₁, b₂; a₂, b₂ being=0 in formula (A-II) to give theepoxydized disiloxane (A-III).
 7. The method of claim 5, wherein saidcomposition further comprises: at least one organic reactive diluentchosen from organic resins containing at least one functional groupselected from the group consisting of expoxide, vinyl ether andoxethane; optionally at least one organic or inorganic pigment;optionally a filler; optionally at least one photosensitizer.
 8. Themethod of claim 5, wherein said support comprises a substrate coated onat least one of its surfaces with at least one layer of siliconeelastomer which is crosslinked or which is at least partiallycrosslinked.
 9. A method of coating a silicone composition as anantifriction varnish upon a support, comprising coating at least onesurface of a support with at least one layer of a silicone compositioncomprising at least one polyorganosiloxane (POS) which is crosslinked bymeans of crosslinking functional groups (CFG) by the cationic and/orfree-radical route and an effective quantity of a cationic initiatorsystem comprising, as thermal initiator and/or photoinitiator, a productchosen from the onium salts of an element of groups 15 to 17 of thePeriodic Table or the salts of an organometallic complex of an elementof groups 4 to 10 of the Periodic Table, whose cationic entity isselected from: 1) the onium salts of formula (I):[(R¹)_(n)-A-(R²)_(m)]⁺  (I) in which formula: A represents an element ofgroups 15 to 17 of the Periodic Table; R¹ represents a carbocyclic orheterocyclic C₆-C₂₀ aryl radical, it being possible for saidheterocyclic radical to contain, as heteroelements, nitrogen or sulfur;R² represents R¹ or a linear or branched C₁-C₃₀ alkyl or alkenylradical, said radicals R¹ and R² being optionally substituted with aC₁-C₂₅ alkoxy, C₁-C₂₅ alkyl, nitro, chloro, bromo, cyano, carboxyl,ester or mercapto group; n is an integer ranging from 1 to v+1, v beingthe valency of the element A; m is an integer ranging from 0 to V−1 withn+m=v+1; 2) oxoisothiochromanium salts; 3) sulfonium salts in which thecationic entity comprises: 3-1) at least one polysulfonium species offormula (III.1)

in which: the symbols Ar¹, which may be mutually identical or different,each represent a monovalent phenyl or naphthyl radical optionallysubstituted with one or more radicals chosen from: a linear or branchedC₁-C12 alkyl radical, a linear or branched C₁-C₁₂ alkoxy radical, ahalogen atom, an —OH group, a —COOH group, an ester group —COO-alkylwhere the alkyl portion is a linear or branched C₁-C₁₂ residue, and agroup of formula —Y⁴—Ar² where the symbols Y⁴ and Ar² have the meaningsgiven just below; the symbols Ar², which may be mutually identical ordifferent, or identical to Ar₁, each represent a monovalent phenyl ornaphthyl radical optionally substituted with one or more radicals chosenfrom: a linear or branched C₁-C₁₂ alkyl radical, a linear or branchedC₁-C₁₂ alkoxy radical, a halogen atom, an —OH group, a —COOH group, anester group —COO-alkyl where the alkyl portion is a linear or branchedC₁-C₁₂ residue, the symbols Ar³, which may be mutually identical ordifferent, each represent a divalent phenylene or naphthylene radicaloptionally substituted with one or more radicals chosen from: a linearor branched C₁-C₁₂, alkyl radical, a linear or branched C₁—C₁₂, alkoxyradical, a halogen atom, an —OH group, a —COOH group, an ester group—COO-alkyl where the alkyl portion is a linear or branched C₁-C₁₂residue, t is an integer equal to 0 or 1, with the additional conditionsaccording to which: a) when t=0, the symbol Y is then a monovalentradical Y¹ representing the group of formula:

where the symbols Ar¹ and Ar² have the meanings given above, b) whent=1: b1) on the one hand, the symbol Y is then a divalent radical havingthe following meanings Y² to Y⁴: Y²: a group of formula:

where the symbol Ar² has the meanings given above, Y³: a single valencybond, Y⁴: a divalent residue chosen from:

a linear or branched C₁-C₁₂ alkylene residue, and a residue of formula—Si(CH₃)₂O—, b₂) on the other hand, only in the case where the symbol Yrepresents Y³ or Y⁴, the radicals Ar¹ and Ar¹ (terminal) possess, inaddition to the meanings given above, the possibility of being linked toeach other by the residue Y′ consisting of Y′¹ a single valency bond orof Y′² a divalent residue chosen from the residues cited in thedefinition of Y⁴, which is seated between the carbon atoms, facing oneanother, situated on each aromatic ring at the ortho position withrespect to the carbon atom directly linked to the cation S⁺; 3-2) and/orat least one mono-sulfonium species possessing a single cationic centerS⁺, per mol of cation and consisting of species of formula (III.2):

in which Ar¹ and Ar² have the meanings given above in formula (III.1),including the possibility of directly linking to one another only one ofthe radicals Ar¹ to Ar² in the manner indicated above in the definitionof the additional condition which applies when t=1 in formula (III.1),involving the residue Y′; 4) the organometallic salts of formula (IV):(L¹L²L³M)^(+q)  (IV) in which formula: M represents a metal of group 4to 10 of the Periodic Table; L¹ represents a ligand linked to the metalM by π electrons, a ligand chosen from the ligands η³-alkyl,η⁵-cycloheptatrienyl and η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η⁶-benzene ligands andthe compounds having from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M by 3 to 8 π electrons;L² represents a ligand linked to the metal M by π electrons, a ligandchosen from the ligands η⁷-cycloheptatrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted η⁶-benzene ligands andthe compounds having from 2 to 4 fused rings, each ring being capable ofcontributing to the valency layer of the metal M by 6 or 7 π electrons;L³ represents from 0 to 3 identical or different ligands linked to themetal M by σ electrons, ligand(s) chosen from CO and NO₂ ⁺; the totalelectron charge q of the complex to which L¹, L² and L³ contribute andthe ionic charge of the metal M being positive and equal to 1 or 2; theanionic entity having the formula: [X¹X² _(a)R_(b)]⁻ in which formula: aand b are integers ranging, for a, from 0 to 6 and, for b, from 0 to 6with a+b≧2; the symbols X¹ represent elements chosen from groups 3A, 4A,5A of the Periodic Table; the symbols X² represent: a halogen atom witha=0 to 3, an OR functional group with a=0 to 2; the symbols R areidentical or different and represent: a phenyl radical substituted withat least one electron-attracting group, and/or with at least 2 halogenatoms, and this being when the cationic entity is an onium of an elementof groups 15 to 17 of the Periodic Table, a phenyl radical substitutedwith at least one electron-attracting atom or one electron-attractinggroup, and this being when the cationic entity is an organo-metalliccomplex of an element of groups 4 to 10 of the Periodic Table, an arylradical containing at least two aromatic nuclei, optionally substitutedwith at least one element or one electron-attracting group, regardlessof the cationic entity; said composition comprising, in addition, asilane substituted with CFG and hydrolyzable secondary functional groups(SFG), exposing the surface thus coated to actinic radiation and/or to abeam of electrons and/or to heat, so as to cause the crosslinking of thesilicone composition and obtain an antifriction layer, wherein saidsupport comprises a substrate coated on at least one of its surfaceswith at least one layer of silicone elastomer which is crosslinked orwhich is at least partially crosslinked.